I was hoping this would be fixed, as it is an issue with CS5 as well, but it has not changed in this beta.
Say I have three shape layers on the canvas.
I add each shape to its own group.
I then select all three groups and change the opacity to 50%.
The top two groups (in the layer order) will change the group opacity to 50% AND the nested shape layer to 50%, effectively making the nested shape layer 25%.
The bottom most group changes ONLY the group to 50% and not the nested shape, meaning the nested shape has an effective opacity of 50%.
It doesn't seem logical to treat identical groups in different ways so I can only assume this is a bug.
As an aside, I don't see why changing multiple group opacities needs to result in the alteration of nested items. I can't see any practical situations where this would be useful, in fact I personally find it frustrating. In the end I simply select the groups individually to change opacities, one by one, which pretty much renders the utility of simultaneously editing groups redundant... My 2 cents.
Specifically to Pierre's point, are the groups collapsed when they are selected (i.e. the child layers hidden in the collapsed group). More details (step by step) would be useful.
A screen shot of the layer selection prior and after the command or a full video of your process could be useful :
Hi, hopefully this clears it up. (might want to fullscreen for detail, of course)
This only seems to happen when selecting collapsed folders. I find it odd that it affects the bottom most folder differently.
On expanded folders selecting everything (folders plus contents) or just the contents gives the same result
Europe, Middle East and Africa